It is widely known that a seat belt can minimize injuries to the vehicle operator in case of a vehicle crash. The traffic law requires the vehicle operator to wear a seat belt. However, unfortunately, there still are some people who do not fully appreciate the importance of the seat belt, and fail to wear the seat belt when traveling in a motor vehicle.
Therefore, various alarm systems have been proposed to the end of urging the vehicle operator to wear a seat belt. For instance, Japanese utility model publication No. 62-29319 discloses an alarm device that issues a warning when the seat belt is not worn and the vehicle speed is higher than a prescribed level.
However, conventional devices of this kind have a problem. Because the alarm is issued only once when the vehicle speed has reached the prescribed level, for instance, as is the case with the invention disclosed in the utility model publication mentioned earlier, the alarm is simply lost when the alarm is disregarded by the vehicle operator. Conversely, if the alarm is issued constantly, the vehicle operator may find it so annoying that he or she may stop using the vehicle.
Also, because conventional devices of this kind simply lights up a warning lamp and emits a warning sound, a vehicle operator not accustomed to the particular vehicle may be unable to comprehend the meaning of the warning. This is not desirable because it causes a discomfort to the vehicle operator.
Furthermore, because other alarm devices such as a warning against failure to release a parking brake and a warning that a reverse range is selected have been added to the vehicle, the vehicle operator may well confuse the warnings particularly when a plurality of alarms are issued at the same time as the seat belt alarm.